Current failure indicator



United States Patent O CURRENT FAILURE INDICATOR Howard I. Podell,Mamaroneck, N. Y.

Application January 6, 1954, Serial No. 402,425 Claims. (Cl. 340-250)This invention relates to automatic indicating systems for electricalnetworks and more specifically to a new and improved circuit andarrangement of components for providing a visual indication upon theinterruption of current through one or more load circuitspowered by alow voltage supply.

Many systems have been developed for use in connection with power supplyand distribution systems to indicate interruption of power in aparticular part thereof through overloading the circuits and causing theprotecting devices such as circuit breakers or fuses to break thecircuit. In conventional 110 volt systems where voltage limitations donot present a problem, conventional lamps or other indicators may beused. Gas filled lamps such as neon tubes and the like can be employedon such power systems wherein the nominal voltage is above the startingvoltage for the gas tube by directly connecting them across the circuitbreaking means. In low voltage circuits, however, and particularly inportable low voltage systems wherein efliciency in the utilization ofpower is of prime importance, prior alarm and indicating systemsknown-to me are not directly applicable and complicated and expensivemechanical systems have therefore been used. Accordingly, this inventionhas as one of its objects a new and improved alarm system for lowvoltage circuits characterized by its simplicity, low cost,instantaneous action and dependability. These ends are accomplishedthrough the provision of a circuit including cold cathode gas filledindicating lamps wherein a lamp immediately responds to the interruptionof current through one or more loads and thus imparts to the operatorinformation concerning the condition of the circuits at all times. 2

Another object of the invention is a new and improved alarm system forlow voltage electric distribution' systems that will draw negligiblecurrent and at the same time not only detect failure of current througha load circuit by reason of the opening of a fuse, switch, or circuitbreaker but also provide an alarm upon the failure of current in a loadcircuit produced by failure of a load to draw current by reason of anopen switch or fuse in the load itself.

' Still another object of the invention is an improved electricalnetwork alarm and indicating system that not only provides an indicationof the condition of the network at all times but also provides means forperiodically testing the alarm system to ascertain its operativeness anddetermine whether or not the alarm system or part thereof has failed.

Theabove and other objects and advantages of the invention will becomemore apparent from the following description and accompanying drawingsforming part of this application.

In the drawings:

Fig. 1 is a circuit diagram illustrating one embodiment of-theinvention; I

"ice

Fig. 2 is a circuit diagram showing another embodiment of the invention;and

Fig. 3 is still another modification of the invention.

Briefly the invention provides an improved alarm or indicating circuitembodying one or more gas filled lamps, such as neon lamps or the likecoupled with an electrical distribution network and a supplementalsource of power so that failure of current in a given section of thenetwork will produce a voltage in series with an associated lamp and thesupplemental source so that the total voltage impressed upon the lampwill be sufficient to cause it to ionize and glow. With this circuiteach indicating lamp may be located adjacent the load or fuse or it maybe at a remote location depending upon the requirements of the specificapplication. More specifically and with reference to Fig. l whichillustrates an electrical power distribution system and an alarmv inaccordance with the invention, the primary source of power is indicatedby a battery 10 connected between two energy distributing conductors 11and 12. A series of. loads such as motors, heaters, or other radio orelectrical equipments are denoted by the numerals 13 to 16 inclusive.The terminals 13 to 16 of each load are connected directly to theconductor 12 while the other terminals13 to 16" are connected throughcurrent interrupting means 17 to 20 inclusive to the other conductor 11.The current interrupting means 17 to 19 are illustrated as fuses whichfunction to open the circuit to the load in the event excess current isdrawn. It is evident that circuit breakers or switches may be used inplace of the fuses without modifying or otherwise altering the alarmcircuit. This is illustrated in connection with load 16 wherein switch20 is in series therewith.

The alarm system includes a separate source of power represented by. thebattery 21 connected between conductor 11 and an alarm conductor 22. Thebattery 21 is phased with the battery 10 so that their voltages will addand the total voltage will be measurable between conductors 12 and 22. Abank of neon lamps or other equivalent low current indicators 23 areconnected to the conductor 22 and through associated resistors 27 to 30to the terminals 13" to 16" of the respective loads. With thisarrangement should the fuses 17 to 19 or switch 20 be open, theassociated neon light 23 to 26 will then receive the sum of the voltagesof sources 21 and 10. In the case of the load 13, should fuse 17 open,the total voltage of the system would be applied to the neon tube 23through the series circuit including resistor 27 and load 13 with theresistor 27 functioning as a current limiting device so that the drainof the tube will be maintained at a negligible value.

In order to test the system to determine whether or not the auxiliarybattery 21 or other power source has sufficient voltage so that the sumof it and the primary source is suflicient to ionize and illuminate theneon lamps 23 to 26, a test circuit is provided. This circuit includestwo series connected resistors 31 and 32 and a series switch 33connected between the conductors 12 and 22. A neon test'lamp 34 isconnected in parallel with the resistor 31. The resistors 31 and 32 areproportioned one relative to the other so that the ionizing voltageapplied to lamp 34, when switch 33 is closed, is only slightly abovethat required by the lamp 34 with both the power sources 21 and 10 atnormal voltage. In this way lighting of lamp 34 in the test circuit willindicate that battery 21 not only has sufficient voltage to illuminatelamps 23 to 26 as described but is well beyond the critical value.

The foregoing embodiment of the invention illustrates the advantages ofthis improved alarm system in power networks where the nominal supplyvoltage is below that required to ionize a neon lamp. Moreover the neonlamps draw only negligible current so that the auxiliary supply needonly be a miniature battery of the desired potential. In the case of A.C. systems, the auxiliary supply 21 must of course be phased with :thebasic supply 1% in order to get the effect. If desired the auxiliarysupply 21 in an A. C. system may comprise a D. C. source in which casephasing is unnecessary.

Fig. 2 is another embodiment of the invention wherein a single lamp isused to indicate failure of current through one or more loads. As in thecase of Fig. 1 the loads 35, 36, and 27 in series with their associatedfuses 39 to 46 are connected between supply conductors 11 and 12 whichin turn connect with the primary source 10. The signalling or alarmsystem includes a single neon tube indicator 41 having one sideconnected through separate resistors 42, 43, and 44 to the fuse side ofthe loads 35 to 37, respectively. The other side of the lamp 41 isconnected through resistor 45 to one terminal of the auxiliary source 21and which has its other terminal connected to conductor 11. With thecircuit thus far should one of the fuses, as for instance fuse 3.8,open, the sum of voltages 21 and will be applied to the neon lamp 41through load and resistors 42 and 45. The shortcircuiting efiect ofresistors 43 and 44 will be negligible since their values usually exceed100,000 ohms. The resistor 45 is optional and would only be used ininstances wherein the sum of the voltages sources 21 and Ill isrelatively high and added current limiting, over and above that providedby resistors 42 to 44, is needed.

The test circuit includes a series connected switch 46 and resistor 47coupled between the conductor 12 and the junction of lamp 41 withresistors 42 to 44. When switch 46 is closed the total voltage isapplied to lamp 41 through resistors 47 and 45 in order to illuminate itand check its operation. The resistor 47 is of course proportionedrelative to the other resistors so that an ionizing volta e onlyslightly in excess of that required is applied to the lamp. In this waythe increased voltage on the lamp 41 when current through one of theloads is interrupted will be considerably above the critical ionizingvoltage.

In certain instances, it may be desirable to indicate not only theopening of a fuse in series with a load but also opening of the loaditself through a failure which not only blows the fuse but also causesthe load itself to open. This end may be accomplished with a circuitconfiguration as shown in Fig. 3. While only a single load isillustrated it will become apparent that the system may be used with anynumber of loads. figure the load 43 with a series connected fuse 49 isconnected across the primary source of power 10. The indicator lamp 549has one side connected to the auxiliary source 21 which in turn isconnected with the primary source 10. The other side of lamp 50 isconnected through series resistors 51 and 52 to one side of load 48while the juncture of resistors 51 and 52 is connected to the junctureof fuse 49 and load 48. Now in the event the fuse 49 opens, theindicator 50 will be illuminated by the total voltage of sources throughthe circuit including load 48 and resistor 51. Should the 102141 48 beopened in addition to blowing of the fuse 49 the indicator 55 will stillbe illuminated by reason of the interconnection of the resistor 52 withresistor 51 and load 48.

The embodiment of the invention of Fig. 3 may of course be used inconnection with the embodiments of Figs. 1. and 2 and similar testcircuits may be employed.

While only certain embodiments of the invention have been shown anddescribed it is apparent that other modiiications, changes andalterations may be made without departing from the true scope and spiritthereof.

Having thus described my invention, .1 claim:

In an electrical power distribution system having a primary source ofpower, means for connecting at In this I least one load therewith andcurrent interrupting means in series with said load, an alarm forindicating failure of current in said load comprising an auxiliary powersource having one terminal connected to one side of said primary powersource, a cold cathode indicator lamp having an ionizing voltage greaterthan the voltage of said primary power source and greater than thevoltage of said auxiliary power source and less than the combinedvoltage of the auxiliary power source and the primary voltage source, aconnection between one terminal of said lamp and the other terminal ofsaid auxiliary source and a connection between the other terminal ofsaid lamp and the junction of said interrupting means and said loadwhereby opening of said interrupting means will apply a voltage to saidlamp approximately equal to the sum of said power sources.

2. In an electrical power distribution system according to claim 1wherein said alarm system includes a current limiting resistor in serieswith said indicator lamp.

3. In an electrical power distribution system according to claim 1wherein said alarm system includes a current limiting resistor in serieswith said indicator lamp and a second resistor in parallel with saidload.

4. In a power distribution system having a primary source of power,means for connecting at least one load therewith and currentinterrupting means in series with said load, an auxiliary power supply,a cold cathode indicator lamp having an ionizing voltage greater thanthe voltage of either the primary source of power and the auxiliarypower supply separately and less than their combined voltages, aconnection between one terminal of said auxiliary source and saidprimary power source to place both of said sources in series one withthe other, a connection between one terminal of said indicator lamp andthe other terminal of said auxiliary power source, and connectionsbetween the other terminal of said lamp and the junction of each of saidloads with its associated current interrupting means, wherebyinterruption of current through one or more loads will apply anincreased voltage to said indicator lamp to illuminate it.

5. In a power distribution system according to claim 4 wherein eachconnection between said lamp and each of said loads includes a currentlimiting resistor.

6. In a power distribution system according to claim 4 wherein eachconnection between said lamp and said loads includes a current limitingresistor and wherein means including a switch and a current limitingresistor is connected between said other terminal of said lamp and theprimary power source whereby closing of said switch will apply thevoltage of both of said sources to said lamp to test the operationthereof.

7. In a power distribution system according to claim 4 wherein eachconnection between said lamps and each of said loads includes a currentlimiting resistor and each of said loads is provided with a resistorconnected in parallel therewith.

8. A power distribution and current vfailure alarm system comprising aprimary power source and an auxiliary power source connected in seriesone with the other to provide a voltage equal to their sum across theouter terminals of said sources, means for connecting at least one loadacross said primary source with current interrupting means in theconnection between said load and the junction of said power sources, acold cathode indicating lamp having one terminal connected to the outerterminal of said auxiliary source and the other terminal to the junctureof said load and current interrupting means, said cold cathodeindicating lamp having an ionizing voltage greater than the voltage ofeither said primary source and said auxiliary power source separatelybut less than their combined voltages.

9. A power distribution and alarm system according to claim 8 whereinsaid cold cathode indicator lamp includes a current limiting resistor inseries therewith.

10. In an electrical power distribution system having a primary sourceof power, means for connecting a plurality of loads therewith and acurrent interrupting means in series with each of said loads, an alarmfor indicating failure of current in each of said loads comprising anauxiliary power source having one terminal connected to one side of saidprimary power source, a plurality of cold cathode indicator lamps eachhaving an ionizing voltage greater than either the voltage of saidprimary power source and said auxiliary power source separately and lessthan the combined voltages of the primary source of power and theauxiliary power source, a connection between one terminal of each ofsaid lamps and the other terminal of said auxiliary source and aconnection between the other terminal of each of said lamps and thejunction of one of said interrupting means and its connected loadwhereby opening of each of said interrupting means will apply a voltageto its connected lamp approximately equal to the sum of said powersources.

References Cited in the file of this patent UNITED STATES PATENTS2,036,223 Lapple Apr. 6, 1936 2,317,030 Colvin Apr. 20, 1943 2,464,848Collins Mar. 22, 1949

